A prosecutor at the trial of three construction supervisors charged in the deaths of two firefighters at the former Deutsche Bank building told the jury on Monday that the defendants had "put profit over people," a decision that led to the deaths and put the lives of hundreds of firefighters, inspectors and workers at risk.

The prosecutor, Assistant District Attorney Brian J. Fields, laid out the government's case in his opening statement on the first day of the trial, saying that it was "all about money" and that "the evidence will establish that defendants took that risk for money -- they gambled with lives for money."

The three men, and the demolition contractor for which two of them worked, the John Galt Corporation, are charged with manslaughter and criminally negligent homicide.

The evidence, Mr. Fields said, will also establish "that these defendants knew the building was a death trap."

"In order to take a risk, you need to know that something very bad could happen," he told the jury in State Supreme Court in Manhattan. "And these defendants knew, these defendants knew that something very bad was going to happen in the Deutsche Bank building."

The 41-story tower, damaged during the Sept. 11, 2001, attacks, was in the process of being torn down -- workers were simultaneously removing asbestos and deconstructing the building, floor by floor -- when a cigarette sparked the fire on Aug. 18, 2007.

Two of the hundreds of firefighters who responded, Robert Beddia, 53, and Joseph P. Graffagnino, 33, were trapped in thick smoke and died on the 14th floor.

The men on trial -- Mitchel Alvo, Salvatore DePaola and Jeffrey Melofchik -- and the Galt company were indicted in 2008. The men face 5 to 15 years in prison if convicted, and Galt faces a $10,000 fine.

Mr. Fields told the jurors that much of the evidence at the trial, expected to last four months, would focus on the removal of a 42-foot section of standpipe that would have allowed firefighters to get water to the building's upper floors and fight the fire.

Without that standpipe system, which is required by law, it took more than an hour to get water to the affected floors, he said, and by then the fire was out of control.

The pipe was removed even though the men knew that the building was in constant danger of fire, Mr. Fields said: torches were being used to cut steel, creating slag -- dripping molten metal that burned whatever it touched -- in a building filled with debris, plywood and other flammable material. Indeed, he said, fires were breaking out with worrisome regularity in the days leading up to the fire.

Justice Rena K. Uviller has ordered lawyers involved in the case to not talk about it to the news media. But in court papers, the lawyers for the three men, Edward J.M. Little, Rick J. Pasacreta and Susan D. Hoffinger, argued that the city, the general contractor, Bovis Lend Lease LMB and various regulatory agencies were more to blame for the deaths than their clients.

Mr. Alvo and Galt have waived their rights to a jury trial; their fates will be decided by Justice Uviller. A jury will weigh the cases of Mr. DePaola and Mr. Melofchik. The defense lawyers are expected to make their opening statements on Tuesday.

The indictments followed an extensive investigation by the district attorney's office. The inquiry focused on the conduct of the city and its agencies, Bovis and the Lower Manhattan Development Corporation, the state agency that owned the building and approved of Bovis's hiring of Galt.

The city and Bovis ultimately acknowledged responsibility for the deaths. But Robert M. Morgenthau, who was then the Manhattan district attorney, concluded that a state law that makes local governments immune from prosecution would have led to a reversal on appeal if there was a conviction of the city or the Buildings and Fire Departments, whose many failures were cited in contributing to the building's unsafe conditions.